C# 读取 CSV 文件

最近做一个C#项目要导入CSV文件中的数据到Oracle中，使用Aspose.Cells读取中文字段标题却乱码，表的最后多出几行null记录，而且不是免费的，后来找到了NPOI，顾名思义，就是POI的.NET版本，POI是一套用Java写成的库，能够帮助开发者在没有安装微软Office的情况下读写Office 97-2003的文件，支持的文件格式包括xls, doc,
ppt等。而且是免费的，学了半天，得出一个结论，杀鸡用牛刀。最后决定自已写一个读取及写入CSV文件的代码，效果非常好。现分享受应趣的朋友门。

using System;

using System.Data;

using System.IO;



namespace DBUtility

{

    public static class CsvHelper

    {

        /// <summary>

        /// 写入CSV文件

        /// </summary>

        /// <param name="dt">DataTable</param>

        /// <param name="fileName">文件全名</param>

        /// <returns>是否写入成功</returns>

        public static Boolean SaveCSV(DataTable dt, string fullFileName)

        {

            Boolean r = false;

            FileStream fs = new FileStream(fullFileName, System.IO.FileMode.Create, System.IO.FileAccess.Write);

            StreamWriter sw = new StreamWriter(fs, System.Text.Encoding.Default);

            string data = "";



            //写出列名称

            for (int i = 0; i < dt.Columns.Count; i++)

            {

                data += dt.Columns[i].ColumnName.ToString();

                if (i < dt.Columns.Count - 1)

                {

                    data += ",";

                }

            }

            sw.WriteLine(data);



            //写出各行数据

            for (int i = 0; i < dt.Rows.Count; i++)

            {

                data = "";

                for (int j = 0; j < dt.Columns.Count; j++)

                {

                    data += dt.Rows[i][j].ToString();

                    if (j < dt.Columns.Count - 1)

                    {

                        data += ",";

                    }

                }

                sw.WriteLine(data);

            }



            sw.Close();

            fs.Close();



            r = true;

            return r;  

        }



        /// <summary>

        /// 打开CSV 文件

        /// </summary>

        /// <param name="fileName">文件全名</param>

        /// <returns>DataTable</returns>

        public static DataTable OpenCSV(string fullFileName)

        {

            return OpenCSV(fullFileName, 0, 0, 0, 0, true);

        }



        /// <summary>

        /// 打开CSV 文件

        /// </summary>

        /// <param name="fileName">文件全名</param>

        /// <param name="firstRow">开始行</param>

        /// <param name="firstColumn">开始列</param>

        /// <param name="getRows">获取多少行</param>

        /// <param name="getColumns">获取多少列</param>

        /// <param name="haveTitleRow">是有标题行</param>

        /// <returns>DataTable</returns>

        public static DataTable OpenCSV(string fullFileName, Int16 firstRow = 0, Int16 firstColumn = 0, Int16 getRows = 0, Int16 getColumns = 0, bool haveTitleRow = true)

        {

            DataTable dt = new DataTable();

            FileStream fs = new FileStream(fullFileName, System.IO.FileMode.Open, System.IO.FileAccess.Read);

            StreamReader sr = new StreamReader(fs, System.Text.Encoding.Default);

            //记录每次读取的一行记录

            string strLine = "";

            //记录每行记录中的各字段内容

            string[] aryLine;

            //标示列数

            int columnCount = 0;

            //是否已建立了表的字段

            bool bCreateTableColumns = false;

            //第几行

            int iRow = 1;



            //去除无用行

            if (firstRow > 0)

            { 

                for (int i=1; i < firstRow;i++)

                {

                    sr.ReadLine();

                }

            }

            

            // { ",", ".", "!", "?", ";", ":", " " };

            string[] separators = { "," };

            //逐行读取CSV中的数据

            while ((strLine = sr.ReadLine()) != null)

            {

                strLine = strLine.Trim();

                aryLine = strLine.Split(separators, System.StringSplitOptions.RemoveEmptyEntries);



                if (bCreateTableColumns == false)

                {

                    bCreateTableColumns = true;

                    columnCount = aryLine.Length;

                    //创建列

                    for (int i = firstColumn; i < (getColumns == 0 ? columnCount : firstColumn+ getColumns); i++)

                    {

                        DataColumn dc

                            = new DataColumn(haveTitleRow == true ? aryLine[i] : "COL" + i.ToString());

                        dt.Columns.Add(dc);

                    }



                    bCreateTableColumns = true;



                    if (haveTitleRow == true)

                    {

                        continue;

                    }

                }



                

                DataRow dr = dt.NewRow();

                for (int j = firstColumn; j < (getColumns == 0 ? columnCount : firstColumn + getColumns); j++)

                {

                    dr[j - firstColumn] = aryLine[j];

                }

                dt.Rows.Add(dr);



                iRow = iRow + 1;

                if (getRows > 0)

                {

                    if (iRow > getRows)

                    {

                        break;

                    }

                }



            }



            sr.Close();

            fs.Close();

            return dt;

        }

    }

}

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